Internet connection sharing (ICS) is a method for connecting multiple computers in a LAN to the Internet through a single connection and a single IP address. ICS typically uses NAT technologies to achieve this and works with most connection technologies, including DSL, cable, ISDN, dial-up and satellite. The device with the modem or broadband interface that establishes the connection to the Internet is called the ICS host, or gateway while the other devices that connect to the Internet via the network and the ICS host are called ICS clients. If the ICS host fails, then all of the ICS clients lose their Internet connection.
Sharing an Internet connection can be achieved through either software or hardware solutions. All versions of Windows from Windows 98 and on have ICS software included in the operating system. However, there are also products such as WinGate and WinProxy, which are third-party shareware alternatives that will turn a computer into a gateway or proxy server. Hardware solutions involve a NAT-based hardware routerthat is connected directly to the Internet connection adapter, and each ICS client is then connected to the router.
Also referred to as simply Internet sharing, on Linux systems, this is called IP masquerading.